Linking Fundamental Investigations and Engineering Results for Extinguishment of Fires on Solid Material

摘要：Vlachos CTS - 9710413这是一项关于固体材料火焰熄灭的研究，因为表面的能量反馈减少，要么是通过表面的直接冷却，要么是通过热或化学剂的氧化流的惰性。本研究采用现代延拓方法对化学反应系统的稳态解进行数值计算。数值结果用一种新的灵敏度分析、简单的火焰熄灭物理模型和标准渐近分析来解释。通过用多孔气体燃烧器模拟热解材料在恒定温度下的燃烧动力学，将气态燃烧动力学与表面能量平衡分离，其中燃料如甲烷或乙烯随氧化剂流动燃烧。研究的一个问题是，当灭绝的关键条件，如无量纲的燃料供应，与Damkohler数无关时。对于化学惰性或活性剂对燃料和/或氧化剂流的各种稀释度以及各种应变率，火焰热反馈到表面的计算是作为质量供应率的函数。对流热反馈和辐射热反馈都包括在内。从史前时代起，人们就开始使用经验灭火方法。在过去的三十年里，已经开发出了复杂的气体火焰熄灭模型，但这些模型很少能应用于固体表面的火焰。热解化学的细节，为大多数固体材料的实际利益是未知的。目前，还没有通用的、可靠的策略来表征各种环境流量和环境条件下固体火灾的熄灭。本项目概述了这种战略；它集成了最先进的流体相和化学模型和非线性系统理论与现有的实验数据和测量技术的灭绝。

Abstract - Vlachos CTS - 9710413 This is an investigation of flame extinction of fires on solid materials occurring because the energy feedback to the surface decreases either by direct cooling of the surface or by inerting of the oxidant stream by a thermal or chemical agent. The study uses modern continuation methods for numerical calculation of stationary-state solutions in chemical reaction systems. Numerical results are interpreted with a novel sensitivity analysis, simple physical models for flame extinction, and standard asymptotic analysis. Gaseous combustion dynamics is separated from the surface energy balance by simulating the pyrolyzing material with a porous gaseous burner at a constant temperature in which a fule such as methane or ethylene burns with the oxidant flow. One isssue examined is when critical conditions for extinction, such as dimensionless fuel supply, are independent of the Damkohler number. The flame heat feedback to the surface is calculated as a function of mass supply rate for various dilutions of the fuel and/or oxidant streams by chemically inert or active agents and for various strain rates. Both convective and radiative heat feedback are included. Empirical methods for extinguishing fires have been used since prehistoric times. In the last thirty years, sophisticated models for extinction in gaseous flames have been developed, but little of this can be applied to fires on solid surfaces. Details of pyrolysis chemistry for most solid materials of practical interest are unknown. At present, no general, robust strategy exists to characterize extinction of solid fires under varioius ambient flow and environmental conditions. Such a strategy is outlined in this project; it integrates state-of-the-art fluid-phase and chemistry models and nonlinear systems theory with available experimental data and measurement techniques for extinction.